The invention relates to an all-wheel distributor transmission of a motor vehicle.
In all-wheel distribution transmissions for motor vehicles known from the practice, a planetary gear set as multiplication step for a switchable off-road gear and an adjustable block for locking between a front axle and a rear axle of the motor vehicle are respectively actuated independently of each other via two separate actuators or electromotors.
However, those all-wheel distributor transmissions with devices for actuating an off-road gearshift and an adjustable lock have the disadvantage of needing a large installation space and working in opposition to the general requirement in motor vehicle technology of a weight reduction to minimize the fuel consumption.
In U.S. Pat. No. 6,022,289 has been described an all-wheel distributor transmission of a motor vehicle in which an off-road gearshift and a lock are actuated via a common drive device. The lock designed here as multi-disc lock is brought by an actuator of the drive device via a lever arm from an open position to a closed position and at the same time to a position that locks a front-wheel input with a rear-wheel input. The off-road gearshift is actuated via a cam disc which converts a rotatory input originating from the actuator to a translatory movement or actuation of the off-road gearshift.
The lock is opened and closed and the off-road gear is engaged or disengaged via the respective direction of rotation of the actuator and of the electromotor corresponding therewith. This means, for example, that a clockwise rotation of the electromotor produces an adjustment of the off-road gear in a shifting position or an adjustment of the multi-disc lock in a closing position. The disengagement of the off-road gear or a locking of the multi-disc lock is produced, for example, by a counterclockwise rotation of the electromotor.
It is here disadvantageous, however, that the different directions of rotation of the electromotor needed for actuation of the multi-disc lock and of the off-road gearshift over their respective overall range of operation cause during the reversal of direction of rotation, a so-called upset play which, specifically in the control of the input for the multi-disc lock, makes only unsatisfactorily possible an exact adjustment of an applied pressure.
It is also disadvantageous that the compression of the discs during the closing or in closed position of the multi-disc lock due to a bending of the lever cannot be exactly defined, since while the discs are compressed, the driving energy of the actuator applied to the multi-disc clutch is partly consumed as lost energy by the deformation of the lever and an exact relationship no longer exists between the compression and the rotation angle of the actuator and the drive shaft thereof respectively.
The problem on which this invention is based is, therefore, to make available an all-wheel distributor transmission for a motor vehicle which needs small installation space and with which can be carried out an exact actuation of an off-road gearshift and of a lock of the all-wheel distributor transmission.
With the inventive all-wheel distributor transmission the constructional expenses and the number of parts are advantageously reduced, since the actuation of the lock and of the off-road gearshift is implemented via a single drive device. The possible compact and low-wear design economizes both installation space and weight and also costs by the reduction of the required parts.
By the fact that the lock and the clutch for the planetary gear set, which serves as multiplication step for the switchable off-road gear, can be actuated via a common drive device and a torque of the drive shaft of the drive device is applied upon the first drive shaft or the second drive shaft of the drive device depending respectively on a control of the switching device for actuation of the lock or of the multiplication step, the expense for control and regulation of the alternative actuation of the lock and of the off-road gearshift is considerably reduced. This advantage results from the fact that there are controlled only one machine such as an electromotor of the drive device that produces the drive torque and only one switching device for rerouting the drive torque from the drive shaft to one of the two drive shafts.